Screw element for use in spinal, orthopedic or trauma surgery and a system of such a screw element and a screw driver adapted thereto

ABSTRACT

A screw element includes a screw axis, a shank for inserting in a bone, and a drive portion for engaging a screw driver. The drive portion includes a first wall defining a first recess and a second wall defining a second recess. Drive grooves are formed in the first wall and extend parallel to the screw axis. The second wall extends axially from a free end portion of the screw element to the first wall and has an inner diameter that continuously increases from the first wall towards the free end portion. A plurality of guide grooves are formed in the second wall at circumferential positions corresponding respectively to circumferential positions of the drive grooves. The guide grooves extend further radially from the screw axis than the drive grooves and guide the screw driver from the free end portion of the screw element to the drive grooves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/830,858, filed Dec. 4, 2017, which is a continuation of U.S. patentapplication Ser. No. 14/685,433, filed on Apr. 13, 2015, now. U.S. Pat.No. 9,867,639, which claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/979,818, filed on Apr. 15, 2014, the contents ofwhich are hereby incorporated by reference in their entirety, and claimspriority from European Patent Application EP 14164692.7, filed on Apr.15, 2014, the contents of which are hereby incorporated by reference iftheir entirety.

BACKGROUND Field of the Invention

The invention relates to a screw element for use in spinal, orthopedicor trauma surgery, and to a screw driver adapted for use with the screwelement. The screw element includes a drive portion for engagement witha screw driver, wherein the drive portion includes drive grooves forengagement with corresponding engagement protrusions of the screwdriver, and guide grooves that are configured to guide the engagementprotrusions of the screw driver into the drive grooves. The screwelement can be used in particular in minimally invasive surgery andother procedures, such as minimal access surgery, where the visibilityof and/or access to the operation site is reduced.

Description of the Related Art

In spinal surgery, surgical techniques are known that include a step ofmounting a receiving part of a polyaxial pedicle screw onto the screwelement in situ after placement of the screw element into the pedicle ofa vertebra. For example, in a surgical technique known as interpedicularminimal access surgery, a small incision is made and several motionsegments of the spine are treated through the small incision. First, thescrew elements with ball-shaped heads are inserted into the pediclesusing an instrument that holds the screw elements so that they do notaccidentally detach from the instrument, and where the instrument alsoacts as a screw driver to insert the screw elements. The screw elementsare inserted into the pedicles to a certain depth that might not be thefinal insertion depth for the screw elements. Then, the actual insertiondepths are determined with the aid of, for example, an X-ray image, andthereafter the screw elements are more precisely adjusted to a finaldesired insertion depth on the basis of the X-ray image. Finally, thereceiving parts are mounted onto the screw elements and a stabilizationrod is connected to the receiving parts.

During the step of adjusting the insertion depth of the respective screwelements, a screw driver that is configured to engage a drive portion ofthe screw element is used. With known screw elements and drivers,locating the drive portion of the screw element may be difficult ifvisibility of the operation site is restricted or if the respectivescrew element is not visible at all.

SUMMARY

Embodiments of the present invention provide a screw element and asystem of a screw element and a corresponding screw driver adaptedthereto that allows for adjustment of an insertion depth of the screwelement in a quick and safe manner.

The screw element permits the screw driver to more easily locate thecorresponding drive portion on the screw element. In addition, the screwelement facilitates insertion of the engagement portion of the screwdriver into the drive portion of the screw element. Therefore, even whenthe screw driver is inserted at a slight incline relative to the screwelement, the design of the drive portion of the screw element helpsalign the screw axis and the axis of the screw driver. Further,operation of the screw driver does not require any complex functions,which allows for easy and convenient handling.

The screw element may be a bone screw with a head that includes thedrive portion. However, the screw element may also be a set screw thatis used as a locking element in a receiving part of a polyaxial bonescrew or in a bone plate. More generally, the screw element may be usedto adjust the position of a screw that has already been placed orimplanted when there is limited or no visibility at the operation site.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparentfrom the description of embodiments by means of the accompanyingdrawings. In the drawings:

FIG. 1 shows a perspective view of a screw element and a portion of ascrew driver adapted to a drive portion of the screw element accordingto a first embodiment of the present invention.

FIG. 2 shows an enlarged view of a detail of FIG. 1.

FIG. 3 shows a perspective view from a top of the screw element of FIGS.1 and 2.

FIG. 4 shows a top view of the screw element of FIGS. 1-3.

FIG. 5 shows a cross-sectional view of the screw element of FIGS. 1-4along line A-A in FIG. 4.

FIG. 6 shows a side view of a screw driver with an engagement portionadapted to the drive portion of the screw element of FIGS. 1-5.

FIG. 7 shows an enlarged perspective view of the engagement portion ofthe screw driver of FIG. 6.

FIG. 8 shows a cross-sectional view of a screw element according to amodified embodiment of the present invention.

FIG. 9 shows an enlarged perspective view of a step of using the screwelement and the screw driver according to the first embodiment.

FIG. 10 shows a perspective view of a step of adjusting an insertiondepth of the screw element according to the first embodiment.

FIGS. 11a-11c show cross-sectional views of steps of engaging the driveportion of the screw element with the engagement portion of the screwdriver according to the first embodiment.

FIG. 12 shows a perspective view of a second embodiment of the screwelement as part of a polyaxial bone anchor.

FIG. 13 shows a perspective view of a further application of the screwelement in connection with a bone plate.

DETAILED DESCRIPTION

Referring to FIGS. 1 to 5, a screw element 1 according to a firstembodiment includes a shank 2 with a bone thread (or a screw thread) 3on at least a portion of the shank 2 and a head 4. The shank 2 isconfigured to be inserted into a bone, for example, into a pedicle of avertebra. A screw axis S is defined by the axis of the bone thread 3.The head 4 has a spherical segment shape and a free end 5 on a side thatis opposite to the shank 2. A drive portion 6 that is configured toengage with an engagement portion of a screw driver is provided at thefree end 5. The drive portion 6 is explained in more detail below.

A system according to an embodiment of the invention includes the screwelement 1 with the drive portion 6 and a screw driver 20 that has anengagement portion 30 adapted for engagement with the drive portion 6 ofthe screw element 1.

As depicted in FIGS. 3 to 5, the drive portion 6 of the screw element 1defines a first recess 7 that is located at a distance from the free end5 and that has an inner wall with a substantially cylindrical maincontour with a main inner diameter and with a cylinder axis coaxial withthe screw axis S. A plurality of longitudinal drive grooves 8 are formedon the inner wall of the substantially cylindrical first recess 7. Thedrive grooves 8 each has a bottom defining or extending along alongitudinal bottom line B_(d) that is parallel to the screw axis S (seeFIG. 5). A cross-section of each of the drive grooves 8, taken along aplane perpendicular to the screw axis S, is substantially circularsegment-shaped. From a top view, the drive grooves 8 are arrangedcircumferentially around the first recess 7 in a star-like manner, asshown in FIG. 4. In one embodiment, the first recess 7 and the drivegrooves 8 together forma torx-shaped drive structure that is configuredto be engaged by a torx-shaped engagement portion of the screw driver.An upper end 7 a of the recess 7 is positioned at a distance from thefree end 5 of the head 4. An axial depth from the upper end 7 a to alower end 7 b of the first recess 7 substantially corresponds to a depthof usual drive recesses for screw elements of this type. In other words,the size of the first recess 7 with the drive grooves 8 is sufficientfor applying a necessary torque for inserting or advancing the screwelement 1.

Between the first recess 7 and the free end 5 is a second recess 9 thatconically tapers and narrows from the free end 5 towards the firstrecess 7. A lower diameter of the second recess 9 may be slightly largerthan the main diameter of the first recess 7 and an upper diameter ofthe second recess 9 is greater than the lower diameter of the secondrecess 9. The depth of the second recess 9 in the axial directioncorresponds to approximately one fifth to one third of the depth of thefirst recess 7, preferably between one fourth and one third of the depthof the first recess 7. The second recess 9 provides an enlarged bevelledsurface that facilitates insertion of the engagement portion 30 of thescrew driver 20 into the drive portion 6.

A plurality of guide grooves 10 are provided in the wall defining thesecond recess 9 at positions corresponding to the positions of the drivegrooves 8 in the first recess 7. Each of the guide grooves 10 has abottom defining or extending along a longitudinal bottom line B_(g) thatis parallel to the screw axis S and also parallel to the bottom lineB_(d) of the corresponding drive groove 8. The bottom lines B_(g) of theguide grooves 10 are farther away from the screw axis S than the bottomlines B_(d) of the drive grooves 8 are from the screw axis S in a radialdirection. Hence, the guide groove 10 is arranged at an axial positionthat is closer to the free end 5 and also extends farther from the screwaxis S in the radial direction than the corresponding drive groove 8.Due to the bevelled surface of the second recess 9, the depth of theguide grooves 10 gradually increases from the free end 5 towards theguide groove 8 relative to the second recess 9. This allows for moreprecise guiding of an engagement protrusion 31 of the screw driver 20into the first recess 7 while simultaneously facilitating the engagementof the engagement protrusion 31 with the outermost portion of the guidegroove 10 at or near the free end 5.

As can be seen from the top view of FIG. 4, each of the guide grooves 10has a greater width than each of the drive grooves 8. A transverse widthof each of the guide grooves 10 decreases along a radial direction fromthe screw axis S towards the bottom line B_(g), and due to the taperingof the second recess 9, a maximum width of each of the guide grooves 10also decreases in a direction towards the free end 5.

The guide grooves 10 connect to (or are in communication with) the drivegrooves 8 through an intermediate section (or an inclined shoulder) 11with a bevelled wall 11 a that conically narrows towards the drivegrooves 8. The intermediate section 11 may have a considerably smalleraxial height than the axial heights of the first recess 7 and the secondrecess 9. Accordingly, the intermediate section 11 and the guide grooves10 form pocket-like recesses that catch and guide the engagementprotrusions 31 of the screw driver 20 into the guide grooves 8.

As depicted in FIGS. 6 and 7, the screw driver 20 includes a drive shaft21, a handle 22 at one end of the drive shaft 21 and the engagementportion 30 at the opposite end of the drive shaft 21. The engagementportion 30 has a substantially cylindrical main contour that fits intothe first recess 7, and longitudinally extending rib-like engagementprotrusions 31 that are sized to engage the drive grooves 8 to applytorque onto the screw element 1. The engagement portion 30 is bevelledtowards a free end surface 32 of the engagement portion 30. The free endsurface 32 is substantially circular. In addition, the engagementprotrusions 31 each have a bevelled front end surface 31 a. The lengthof the bevelled front end surface 31 a of the engagement projections 31corresponds substantially to the length of the conical surface of thesecond recess 9 of the drive portion 6 of the screw element 1, betweenthe free end 5 and the intermediate portion 11. The bevelled front endsurface 31 a may have the same angle of inclination as the conicalrecess 9 or the slanted wall 11 a of the intermediate portion 11. Suchan enlarged bevelled surface facilitates easier location of the driveportion 6 of the screw element 1 even in instances where there islimited visibility or no visibility at the operation site.

A modified embodiment of the screw element with a modified drive portion6 is shown in FIG. 8. All parts and portions that are identical to thefirst embodiment are marked with the same reference numerals and thedescriptions thereof will not be repeated. The modified embodiment ofthe screw element differs in the shape of the intermediate portion. Inthis embodiment, the intermediate portion 11′ is formed by a roundedwall 11 a′.

Referring now to FIGS. 9 and 10, the application of the screw elementand the screw driver according to the first embodiment will beexplained. In FIG. 9, two screw elements 1 have already been insertedinto the pedicles of two vertebrae 100. Each of the screw elements 1includes the drive portion 6 as described above. The insertion depths ofthe screw elements 1 are further adjusted with the screw driver 20 byengaging the engagement portion 30 with the corresponding drive portions6 of the screw elements 1. Due to the design of the drive portion 6 ofthe screw element 1 and the engagement portion 30 of the screw driver20, the engagement portion 30 and the drive portion 6 can be quickly andeasily engaged, even if there is limited or no visibility at theoperation site. Therefore, it is possible to adjust multiple pediclescrews in a short time.

Referring now to FIGS. 11a, 11b, and 11c , the interaction between theengagement portion 30 of the screw driver 20 and the drive portion 6 ofthe screw element 1 is shown in more detail. As depicted in FIG. 11a ,the screw driver 20 may approach the screw element 1 at an inclinerelative to the screw axis S. As further shown in FIGS. 11a and 11b ,the engagement portion 30 of the screw driver 20 may first engage theconical second recess 9. When the engagement protrusions 31 of theengagement portion 30 of the screw driver 20 begin to engage the guidegrooves 10, the screw driver 20 is automatically aligned with the screwelement 1 while penetrating or advancing further into the drive portion6. The guide grooves 10 and the intermediate portion 11 guide theengagement portion 30 into the drive grooves 8, so that the screwelement 1 and the screw driver 20 become aligned and connected in aform-fit manner to each other. Then, torque can be applied with thescrew driver 20 onto the screw element 1. Due to the decreasing depthand width of the guide grooves 10 towards the free end 5 and the bottomlines B_(g), respectively, the engagement portion 30 can be easilyrotated until the engagement protrusions 31 locate and engage theengagement grooves 10.

A second embodiment of a screw element is explained with reference toFIG. 12. Parts and portions that are the same or substantially the sameas the previous embodiments have the same reference numerals and thedescriptions thereof will not be repeated. In the embodiment of FIG. 12,the screw element is a set screw 40 that is used in a polyaxial boneanchoring device 50. The polyaxial bone anchoring device 50 is shownonly in an exemplary manner; many different designs of such polyaxialbone anchoring device may be contemplated. The polyaxial bone anchoringdevice 50 includes a screw element 1′ that has a sphericalsegment-shaped head (not shown) and a drive portion. The drive portionmay be a known drive portion, such as, for example, a known torx-shapeddrive portion or a polygon-shaped drive portion, or may be a driveportion 6 according to the previously described embodiments. The screwelement 1′ is pivotably connected to a receiving part 51 that includes aseat to hold the head of the screw element 1′ in a ball and socketmanner. A pressure element (not shown) may also be provided to exertpressure onto the head. The receiving part 51 also includes asubstantially U-shaped recess 52 that is configured to receive a rod 200therein. The rod 200 may be connected to a plurality of bone anchoringdevices. To lock the rod 200 in the receiving part 51 and a pivotposition of the head relative to the receiving part 51, a lockingelement in the form of a set screw 40 is used that cooperates with athread provided in the receiving part 51. Once the head and the rod arelocked, further adjustments may become necessary. To make suchadjustments, the set screw 40 has to be loosened and tightened againafter correcting the angular position of the receiving part 51 relativeto the head or after correcting the position of the rod 200. For suchadjustments, the screw driver 20 that cooperates with the drive portion6 in the set screw 40 may be used. Hence, the adjustments can beperformed more quickly and easily.

It should be noted that a set screw having the engagement portion 6could also be used for other types of bone anchoring devices, forexample, for a monoaxial bone anchor in which the screw element and thereceiving part are fixed relative to each other.

A further application is shown in FIG. 13. FIG. 13 depicts a bone plate60 that may be used with the screw elements 1, for example, inorthopedic and trauma surgery to immobilize broken bone parts. The screwelements 1 can be the same or similar to those discussed with respect toFIGS. 1 to 5 and 8, where the head of each screw element 1 includes thedrive portion 6. The head may have a spherical segment shape so that thescrew element 1 can be placed and positioned within a hole of the boneplate 60 at various angles. Alternatively, the head may have a shapethat limits positioning of the screw element 1, for example, to a fixedangle with respect to the bone plate 60. When implanting the bone plate60, the insertion depth of the screw elements 1 may need to be adjusted.These adjustments may be made by using the screw element 1 with thedrive portion 6 and a corresponding screw driver 20. In a still furthermodification, a locking element may be provided in the holes of the boneplate 60 to prevent pull-out of the screw elements, where the driveportion 6 is formed on the locking elements.

Further embodiments and modifications of the previously describedembodiments may also be contemplated. For example, the sizes and theangles of the bevelled surface of the second recess 9, of the guidegrooves 8, as well as of the intermediate portion 11, 11′ can be varied.The wall 11 a, 11 a′ of the intermediate portion 11, 11′ may also haveany shape that is configured to guide the engagement portion 30 of thescrew driver 20 into the first recess 7.

In the embodiments shown, an even number of drive grooves 8 are shown,and each drive groove 8 is positioned opposite to another drive groove 8in the drive portion 6. However, an odd number of drive grooves may alsobe contemplated, and one drive groove may not be opposite to anotherdrive groove in the drive portion. This may also apply to thecorresponding guide grooves.

In addition, instead of the torx-shape of the drive grooves, a polygonalshape of the first recess may also be contemplated. In such a case, thecorners of the polygon may be considered the drive grooves.

In some embodiments, the respective bottom lines of the drive groovesand the guide grooves may not align and instead may be arranged in atwisted configuration around the screw axis. Also, the respective bottomlines may not be exactly parallel to the screw axis in some embodiments.

While the present invention has been described in connection withcertain exemplary embodiments, it is to be understood that the inventionis not limited to the disclosed embodiments, but is instead intended tocover various modifications and equivalent arrangements included withinthe spirit and scope of the appended claims, and equivalents thereof.

1. A screw element for use in spinal, orthopaedic, or trauma surgery,the screw element comprising: a screw axis; a shank extending along thescrew axis and configured to be inserted into a bone; and a driveportion configured to engage a screw driver, wherein the drive portioncomprises: a first wall defining a first recess, wherein a plurality ofdrive grooves are formed in the first wall; and a second wall defining asecond recess, wherein the second wall extends axially from a free endportion of the screw element to the first wall, wherein a plurality ofguide grooves are formed in the second wall at circumferential positionsaround the screw axis that correspond respectively to circumferentialpositions of the drive grooves, wherein the guide grooves extend furtherradially from the screw axis than the drive grooves, and wherein a depthand a width of each of the guide grooves decreases as the guide grooveextends from a region adjacent the first wall toward the free endPortion.
 2. The screw element of claim 1, wherein the first recess issubstantially cylindrical and the drive grooves extend substantiallyparallel to the screw axis.
 3. The screw element of claim 1, wherein thefirst recess has a torx-shape.
 4. The screw element of claim 1, whereinthe second recess is substantially conical.
 5. The screw element ofclaim 1, wherein an axial length of the second recess is between onefifth and one half of an axial length of the first recess.
 6. The screwelement of claim 1, wherein each of the guide grooves has a bottom thatextends along a first line, wherein each of the drive grooves has abottom that extends along a second line, and wherein the first line islocated further away from the screw axis than a bottom the correspondingsecond line is from the screw axis. 7-8. (canceled)
 9. The screw elementof claim 1, wherein the width of the guide grooves at a position closestto the first recess is greater than a width of the drive grooves. 10.(canceled)
 11. The screw element of claim 1, wherein the screw elementis a bone screw with at least a portion of the shank comprising a bonethread, wherein the bone screw further comprises a head having the freeend portion on a side opposite to the shank, and wherein the driveportion is provided on the head.
 12. The screw element of claim 11,wherein the head has a spherical segment-shaped outer surface portion.13. The screw element of claim 1, wherein the screw element is a setscrew configured to be used as a locking element for a polyaxial bonescrew or for a bone plate.
 14. A system comprising: the screw element ofclaim 1; and a screw driver configured to engage the drive portion ofthe screw element, the screw driver comprising a drive axis and anengagement portion with engagement protrusions each extending parallelto the drive axis, wherein the guide grooves of the drive portion areconfigured to engage the screw driver at the free end portion of thescrew element and guide the engagement portion of the screw driver fromthe free end portion of the screw element to the drive grooves.
 15. Thesystem of claim 14, wherein the engagement protrusions form a torx-shapein a cross-sectional plane perpendicular to the drive axis.
 16. A screwelement for use in spinal, orthopaedic, or trauma surgery, the screwelement comprising: a screw axis; a shank extending along the screw axisand configured to be inserted into a bone; and a drive portionconfigured to engage a screw driver, wherein the drive portioncomprises: a first wall defining a first recess, wherein a plurality ofdrive grooves are formed in the first wall; and a second wall defining asecond recess, wherein the second wall extends axially from a free endportion of the screw element to the first wall, wherein in a firstradial direction relative to the screw axis, a distance between thescrew axis and the second wall continuously increases from the firstwall to the free end portion, such that the second wall in its entiretyis inclined relative to the screw axis in the first radial direction,wherein a plurality of guide grooves are formed in the second wall atcircumferential positions around the screw axis that correspondrespectively to circumferential positions of the drive grooves, theguide grooves extending further radially from the screw axis than thedrive grooves.
 17. The screw element of claim 16, wherein the firstrecess has a torx-shape.
 18. The screw element of claim 16, wherein thescrew element is a bone screw with at least a portion of the shankcomprising a bone thread, wherein the bone screw further comprises ahead having the free end portion on a side opposite to the shank, andwherein the drive portion is provided on the head.
 19. The screw elementof claim 16, wherein the screw element is a set screw configured to beused as a locking element for a polyaxial bone screw or for a boneplate.
 20. A screw element for use in spinal, orthopaedic, or traumasurgery, the screw element comprising: a screw axis; a shank extendingalong the screw axis and configured to be inserted into a bone; and adrive portion configured to engage a screw driver, wherein the driveportion comprises: a first wall defining a first recess, wherein aplurality of drive grooves are formed in the first wall; and a secondwall defining a second recess, wherein the second wall extends axiallyfrom a free end portion of the screw element to the first wall, whereina plurality of guide grooves are formed in the second wall atcircumferential positions around the screw axis that correspondrespectively to circumferential positions of the drive grooves, theguide grooves extending further radially from the screw axis than thedrive grooves, and wherein a plurality of intermediate sectionsrespectively connect the guide grooves to the drive grooves, theintermediate sections each having a same first inclined cross-sectionalprofile, and the intermediate sections being circumferentially spacedapart from each other by regions of the drive portion that have across-sectional profile that is different from the first inclinedcross-sectional profile.
 21. The screw element of claim 20, wherein theregions of the drive portion that circumferentially space apart theintermediate sections from one another comprise portions of the firstwall.
 22. The screw element of claim 20, wherein the intermediatesections each comprises a bevelled wall that conically narrows from theguide groove toward the drive groove.
 23. The screw element of claim 20,wherein the intermediate sections each comprises a rounded wall thatnarrows from the guide groove toward the drive groove.